Nacelle mountable lift system for a wind turbine

ABSTRACT

A lift system mountable in a nacelle of a wind turbine has a boom having a proximal end mountable in the nacelle and a distal end extending over a hub of a rotor of the wind turbine when the lift system is mounted in the nacelle. The lift system has a frame structure for mounting the proximal end of the boom in the nacelle, a winch mounted to the boom, a fastener situated below the boom and operatively connected to the winch by at least one cable, and a trolley movably mounted to the boom to permit translation of the trolley longitudinally along the boom thereby permitting longitudinal movement of the fastener with respect to the boom.

This application is a national entry of PCT/CA2019/050568 filed May 1,2019 and claims the benefit of United States Provisional PatentApplications U.S. Ser. No. 62/775,687 filed Dec. 5, 2018 and U.S. Ser.No. 62/667,458 filed May 5, 2018, the entire contents of all of whichare herein incorporated by reference.

FIELD

This application relates to lift systems, especially to a liftingappliance mountable on wind turbines.

BACKGROUND

Wind turbines require periodic maintenance to remain operable. Due tothe extreme height at which many wind turbines operate, maintainingand/or replacing turbine parts (e.g. a rotor, blade, main bearing, mainshaft, intermediate shaft, gearbox, etc.) becomes problematic. Forreasons of safety and practicality, turbine parts are generally loweredto ground level for maintenance and/or replacement. Typically, a craneis used to lower (and then re-raise) the parts to be maintained orreplaced.

There have been a number of cranes developed in the prior artspecifically adapted for maintenance of various parts of the windturbine. For example, the cranes disclosed in co-pending U.S. patentapplications Ser. No. 15/916,364 filed Mar. 9, 2018 and 62/589,778 filedNov. 22, 2017, the entire contents of both of which are hereinincorporated by reference, are capable of lifting various turbinecomponents, as well as lifting part of other cranes that can be mountedon the wind turbine.

However, there still remains a need for a turbine-mounted crane that iscapable of lifting, moving and lowering heavy turbine components, suchas a fully-assembled rotor and/or a fully-assembled main shaft assembly.

SUMMARY

In one aspect, there is provided a lift system mountable in a nacelle ofa wind turbine, the lift system comprising: a boom comprising a proximalend and a distal end, the proximal end of the boom mountable in thenacelle, the distal end of the boom extending over a hub of a rotor ofthe wind turbine when the lift system is mounted in the nacelle; a framestructure for mounting the proximal end of the boom in the nacelle; awinch mounted to the boom; a fastener situated below the boom andoperatively connected to the winch by at least one cable; and, a trolleymovably mounted to the boom to permit translation of the trolleylongitudinally along the boom thereby permitting longitudinal movementof the fastener with respect to the boom.

In some embodiments, the boom may be a beam or a truss structure. Theboom may extend longitudinally with respect to a major axis of thenacelle when the lift system is mounted in the nacelle. To extendlongitudinally, the boom does not need to be exactly parallel to thelongitudinal axis of the nacelle, but can be angled by an amount, forexample about 20° or less, preferably about 10° or less, horizontallyand/or vertically with respect to the longitudinal axis of the nacelle.Preferably, the boom is substantially not angled horizontally withrespect to the longitudinal axis of the nacelle. Preferably, the boom isangled vertically with respect to the longitudinal axis of the nacelleby an amount of about 10° or less.

In one embodiment, the frame structure comprises a mounting basemountable on a structure capable of supporting all forces imparted tothe nacelle by the lift system including the weight of the lift system,for example pillow blocks of a gearbox of the wind turbine, a bedplate,a generator, etc. In one embodiment, the frame structure comprises aplurality of upwardly extending support struts. In one embodiment, atleast one of the support struts is supportable on the mounting base. Inone embodiment, at least one of the support struts is mountable at aposition in the nacelle proximate a main bearing of the wind turbine,for example on a yaw drive mount. In one embodiment, the plurality ofupwardly extending support struts comprises a first strut mountable onthe mounting base over a first gearbox pillow block of the nacelle, asecond strut mountable on the mounting base over a second gearbox pillowblock of the nacelle, a third strut mountable at a first position in thenacelle proximate the main bearing, for example on a first yaw drivemount of the nacelle, and a fourth strut mountable at a second positionin the nacelle proximate the main bearing, for example on a second yawdrive mount of the nacelle.

In one embodiment, the winch is mounted on an upper surface of the boom.In one embodiment, the winch is mounted underneath the boom. In oneembodiment, the at least one cable comprises first and second cables,and the first and second cables between the winch and the fastener pass,respectively, on first and second transverse sides of the boom so thatthe cables do not interfere with longitudinal translation of the trolleyon the boom. In one embodiment, lengths of the first and second cablesare independently adjustable to permit steering a load connected to thefastener. In one embodiment, the first cable is linked to a firsthydraulic cylinder mounted on the first side of the boom and the secondcable is linked to a second hydraulic cylinder mounted on the secondside of the boom. In one embodiment, the links are direct connections ofthe cables to the hydraulic cylinders, although in other embodiments thelinks may be formed with linking structures between the cables and thehydraulic cylinders. The first and second hydraulic cylinders may beindependently actuatable to independently adjust the lengths of thefirst and second cables.

In one embodiment, the wind turbine further comprises a main drive shaftmounted in the nacelle, the main drive shaft having a longitudinal axisoriented at a non-zero angle away from horizontal. In one embodiment,the boom has a longitudinal axis substantially parallel to thelongitudinal axis of the main drive shaft. In one embodiment, thetrolley translates longitudinally along a path substantially parallel tothe longitudinal axis of the main drive shaft.

In one embodiment, the trolley extends transversely beyond thetransverse sides of the boom. In one embodiment, the trolley comprises afirst trolley sheave on a first transverse side of the boom and a secondtrolley sheave on a second transverse side of the boom, and the cablesare reeved through the first and second trolley sheaves. Each of thefirst and second trolley sheaves may comprise one sheave or more thanone sheave disposed side-by-side. In one embodiment, the winch ismounted on the trolley and moves with the trolley.

In one embodiment, the trolley comprises two or more movably connectedpieces, for example two movably connected pieces, which can moverelative to each other, for example in directions transverse to thedirection of travel of the trolley, to permit yawing the load on thelift system. The two or more pieces may be movably connected, forexample, by linkages, actuators or a combination thereof. For example,if the first and second hydraulic cylinders are independently actuatableand one or more linear bearings bridge the two or more pieces, asuitable arrangement would be provided.

The lift system of the present invention is safer, less costly and morereliable than existing cranes for lifting very heavy components (e.g. afully-assembled rotor, a fully assembled main shaft assembly) of windturbines. The lift system of the present invention reduces or eliminatesthe need for large ground-based cranes to making corrective repairs tosuch wind turbine components. The lift system of the present inventionis a nacelle-mountable system having a lifting capacity of up to atleast 75 tonnes, and which can perform the same lifting work as a600-ton conventional ground-based crane, while being easily mobilized toa site in fewer standard ISO containers.

The present lift system has all required rigging at the top of the windturbine when mounted in the nacelle and does not require ground-basedrigging or support cables running down to the ground, although a powercable may still be required in some cases to run from the generator tothe ground. Therefore, the present lift system permits the rotor of thewind turbine to be turned into the wind when the lift system isinstalled and used, which reduces undesirable wind shear on the nacelleduring erection and de-erection of wind turbine components. The presentlift system also permits placing the rotor blades in the requiredposition relative to the ground.

Further features will be described or will become apparent in the courseof the following detailed description. It should be understood that eachfeature described herein may be utilized in any combination with any oneor more of the other described features, and that each feature does notnecessarily rely on the presence of another feature except where evidentto one of skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

For clearer understanding, preferred embodiments will now be describedin detail by way of example, with reference to the accompanyingdrawings, in which:

FIG. 1 depicts a schematic drawing of a front perspective view of a liftsystem mounted on a nacelle of a wind turbine;

FIG. 2 depicts a top view of the lift system of FIG. 1;

FIG. 3 depicts a side view of the lift system of FIG. 1 holding adismounted rotor;

FIG. 4 depicts the lift system of FIG. 3 lowering the rotor;

FIG. 5 depicts a schematic drawing of a wind turbine on which the liftsystem of FIG. 4 is mounted, the rotor having been lowered;

FIG. 6 depicts a schematic drawing of a top perspective view of anacelle of a wind turbine illustrating mounting points for the liftsystem of FIG. 1;

FIG. 7 depicts the lift system of FIG. 1 positioned for removal of amain shaft assembly of the wind turbine;

FIG. 8 depicts the lift system of FIG. 7 with the main shaft assemblyremoved; and,

FIG. 9 depicts a schematic drawing of the lift system of FIG. 1 mountedon the nacelle together with auxiliary cranes used to mount the liftsystem on the nacelle.

DETAILED DESCRIPTION

With reference to the Figures, a lift system 1 mountable on a nacelle101 of a wind turbine 100 comprises a cantilevered beam 5, a framestructure 10 on which the beam 5 is supported and a winch 20 mounted onthe beam 5.

The frame structure 10 comprises first, second, third and fourthupwardly extending struts 11, 12, 13, 14, respectively, connected to aproximal end 6 of the beam 5. The first and second struts 11, 12,respectively, are connected at the very end of the proximal end 6 whilethe third and fourth struts 13, 14, respectively, are connected to theproximal end 6 at a position longitudinally forward, with respect to thebeam 5, of first and second struts 11, 12. The frame structure 10comprises a base 15 on which the first and second struts 11, 12 aremounted. The base 15 is mountable on first and second front gearboxpillow blocks 81, 82, respectively, of the nacelle 101 (see FIG. 6),although the base 15 may be mountable on any structure in the nacelle101 capable of supporting the weight of the lift system. The third andfourth struts 13, 14 are mountable on first and second yaw drive mounts83, 84, respectively, of the nacelle 101 (see FIG. 6). The framestructure 10 further comprises a plurality of cross-braces 16 betweenthe struts 11, 12, 13, 14 to provide structural rigidity to the framestructure 10. While the proximal end 6 of the beam 5 is supported on theframe structure 10, a distal end 7 of the beam 5 extends longitudinallyforwardly, with respect to a major axis of the nacelle 101, which islaterally forward with respect to a vertical axis of the wind turbine100 The distal end 7 of the beam 5 extends over a hub 102 of a rotor 103of the wind turbine 100.

The winch 20 comprises a spool with two spool halves 21, 22 mounted atopthe beam 5 at the proximal end 6 of the beam 5 so that the weight of thewinch 20 is borne by the frame structure 10. A trolley 23 is mounted ontrolley skidding track 8 on an upper surface of the beam 5. The trolley23 is movable by sliding longitudinally along the beam 5 on the trolleyskidding track 8. In one embodiment, the trolley 23 may comprise abracket that engages the upper and side surfaces of the beam 5 and thetrolley skidding track 8 may comprise one or more hydraulic cylinders,with the trolley 23 mounted to one or more cylinder rods of the one ormore hydraulic cylinders, whereby actuation of the one or more hydrauliccylinders to extend and retract the cylinder rods causes the trolley 23to move longitudinally on the beam 5. The trolley 23 may ride or slideon bearings between the bracket and the beam 5, if desired.

Cables 26, 27 wound around the spool halves 21, 22, respectively,connect the winch 20 to a fastener block 25 situated below the beam 5.The spool is driven by a motor so that the two spool halves 21, 22 aredriven simultaneously at the same speed. The cables 26, 27 are isolatedon to their respective spool halves 21, 22 by a divider. The cables 26,27 are reeved from the spool halves 21, 22 through forward sheaves 31,32, respectively, mounted on the distal end 7 of the beam 5. From theforward sheaves 31, 32, the cables 26, 27 are reeved through trolleysheaves 33, 34, respectively, mounted and moveable with the trolley 23.From the trolley sheaves 33, 34, the cables 26, 27 are reeved throughfastener block sheaves 28, 29, respectively, mounted on the fastenerblock 25. From the through fastener block sheaves 28, 29, the cables 26,27 are reeved back through the trolley sheaves 33, 34, respectively.From the trolley sheaves 33, 34, the cables 26, 27 are reeved throughrearward sheaves 37, 38, respectively, to end terminations on theproximal end 6 of the beam 5. The cables 26, 27 are on opposite sides ofthe beam 5 so that the cables 26, 27 do not interfere with movement ofthe trolley 23 on the beam 5. A hook 30, or other fastener such as alifting lug, is attached to the fastener block 25, the hook 30 dependingdownwardly to be able to fasten to a convenient part of a turbinecomponent, for example the rotor 103 (see FIG. 4) or a main drive shaftassembly 105 (see FIG. 8).

The rearward sheaves 37, 38, are mounted on ends of hydraulic cylinders41, 42, respectively. The opposite ends of the hydraulic cylinders 41,42 are fixedly mounted on the beam 5. Actuation of the hydrauliccylinders 41, 42 adjusts the lengths of the cables 26, 27. The hydrauliccylinders 41, 42 are independently actuatable to so that the lengths ofthe cables 26, 27 can be independently and differentially adjusted.Differential adjustments of the cables 26, 27 causes the rotor 103 tomove slightly to the left or right to allow alignment of the rotor 103with the main drive shaft assembly 105 to be able to mount the rotor 103on the drive shaft even when there is a side-wind that causes the rotor103 to drift. Differential adjustments of the cables 26, 27 may alsoassist aligning the main drive shaft assembly 105 with the bearings andother components mounted in the nacelle 101 so that the main drive shaftassembly 105 may be smoothly withdrawn from the nacelle 101. Sequentialoperation of the hydraulic cylinders 41, 42 effectively permits steeringthe main drive shaft assembly 105 when necessary to smoothly remove themain drive shaft assembly 105 from the nacelle 101 by keeping alongitudinal axis of the main drive shaft assembly 105 aligned with apath required to remove the main drive shaft assembly 105 from thenacelle 101.

As illustrated in FIG. 1 to FIG. 5, the lift system 1 may be used tolower the fully-assembled rotor 103 from atop the wind turbine 100 tothe ground. The hook 30 is attached to the hub 102 with blades 104 ofthe rotor 103 still attached to the hub 102, bolts securing the hub 102to the nacelle 101 are loosened and the trolley 23 is moved to thedistal end 7 of the beam 5. The hub 102 is then dismounted from thenacelle 101 as seen in FIG. 3, and the winch 20 operated to lower therotor 103 as seen in FIG. 4. Because all of the rigging for the liftsystem 1 is located on the wind turbine 100, the rotor 103 can be turnedinto the wind for lowering to prevent wind loading on the rotor 103.Further, the cables 26, 27 are situated forward of the nacelle 101 sothe nacelle 101 does not interfere with lowering the rotor 103. As seenin FIG. 5, a small mobile ground-based crane 90 may be attached to anend of one of the blades 104 simply to help stabilize and guide therotor 103 while the rotor 103 is being lowered. Tag lines (not shown)may also be used on upwardly extending blades 104 to prevent rotation ofthe rotor 103 around an axis perpendicular to a plane of the blades 104.Reversing the procedure can be done to re-install the rotor 103.

As illustrated in FIG. 7 to FIG. 8, the lift system 1 may be used tolower the fully-assembled main drive shaft assembly 105 from atop thewind turbine 100 to the ground. The trolley 23 is moved closer to theproximal end 6 of the beam 5 to a position over the main shaft assembly105 where the hook 30 can be attached to the main shaft assembly 105,for example with the assistance of a lifting tool 35. The lifting tool35 may comprise an adjustment tool 36 (e.g. a manual or a hydraulictool) to change the angle of the main drive shaft assembly 105. The maindrive shaft assembly 105 is slightly angled when mounted in the nacelle101 relative to the horizontal to account for wind loading on the rotorblades 104 to prevent interference between the rotor blades 104 and atower 106 of the wind turbine 100 when the wind is blowing. The angle ofthe main drive shaft assembly 105 is generally in a range of about 3-10°with respect to the horizontal, preferably 3-8°, for example about 6°.In order to remove the rotor 103 from the nacelle 101, the rotor 103about must be drawn out at this angle relative to the horizontal. Inorder to remove the main drive shaft assembly 105 from the gearbox, themain drive shaft assembly 105 may need to be drawn out at a steeperangle relative to the horizontal, for example about 8.5°, to be able toclear some stud bolts. Further changing of the angle of the main driveshaft assembly 105 is accomplished with the adjustment tool 36. Theangles are different for different makes of wind turbine, hence a needfor a way of adjusting the angle of the lifting tool 35.

Alternatively to, or in addition to, using the adjustment tool 36, thebeam 5 is mounted on the frame structure 10 at an angle to thehorizontal, the angle of the beam 5 matching the angle of the main driveshaft assembly 105 so that the trolley 23 moves along the beam 5 along aline parallel to the longitudinal axis of the main drive shaft assembly105, thereby permitting drawing of the rotor 103 off the main driveshaft assembly 105 without the need to use the adjustment tool 36. Theangle of the beam 5 may be adjusted by using third and fourth struts 13,14 of different length to match the main drive shaft assembly angle forthe particular make of wind turbine. The adjustment tool 36 may be usedto further adjust the angle of the main drive shaft assembly 105 afterthe rotor 103 has been drawn off the main drive shaft assembly 105 sothat the main drive shaft assembly 105 can be drawn out of the nacelle101 without the main drive shaft assembly 105 jamming on or otherwisestriking the nacelle 101.

Once the lift system 1 is connected to the main shaft assembly 105, themain drive shaft assembly 105 is disconnected from the nacelle 101. Withthe main drive shaft assembly 105 disconnected from the nacelle 101, thetrolley 23 is moved longitudinally forward to the distal end 7 of thebeam 5 as seen in FIG. 8 so that the main drive shaft assembly 105clears a front 109 of the nacelle 101. The lifting tool 35 or the hook30 may also have a swivel to allow rotation of the main drive shaftassembly 105 to create more clearance for the main drive shaft assembly105 once the main drive shaft assembly 105 clears the front 109 of thenacelle 101. The main shaft drive assembly 105 can then be lowered tothe ground by the winch 20. Reversing the procedure can be done tore-install the main drive shaft assembly 105.

The lift system 1 is very large. To mount the lift system 1 on thenacelle 101, a first auxiliary crane 200 may be used to lift the partsof the lift system 1 up to the nacelle 101 of the wind turbine 100 wherethe lift system 1 is assembled. The first auxiliary crane 200 is also alarge crane, though not as large as the lift system 1. A secondauxiliary crane 300 may be used to lift the parts of the first auxiliarycrane 200 up to the nacelle 101 where the first auxiliary crane 200 isassembled. The second auxiliary crane 300 is also a large crane, thoughnot as large as the first auxiliary crane 200. A third auxiliary crane400 may be used to lift the parts of the second auxiliary crane 300 upto the nacelle 101 where the second auxiliary crane 300 is assembled.The third auxiliary crane 400 may be an existing nacelle-mounted servicecrane that is included with the wind turbine 100 when the turbine 100 isbuilt.

The novel features will become apparent to those of skill in the artupon examination of the description. It should be understood, however,that the scope of the claims should not be limited by the embodiments,but should be given the broadest interpretation consistent with thewording of the claims and the specification as a whole.

The invention claimed is:
 1. A lift system mountable in a nacelle of awind turbine, the lift system comprising: a boom comprising a proximalend and a distal end, the proximal end of the boom mountable in thenacelle, the distal end of the boom extending over a hub of a rotor ofthe wind turbine when the lift system is mounted in the nacelle; a framestructure for mounting the proximal end of the boom in the nacelle; awinch mounted to the boom; a fastener situated below the boom andoperatively connected to the winch by at least one cable; and, a trolleymovably mounted to the boom to permit translation of the trolleylongitudinally along the boom, the at least one cable reeved through atleast one trolley sheave mounted on and moveable with the trolleythereby permitting longitudinal movement of the fastener with respect tothe boom when the trolley translates longitudinally along the boom, theat least one cable comprising first and second cables between the winchand the fastener passing, respectively, on first and second transversesides of the boom so that the cables do not interfere with longitudinaltranslation of the trolley on the boom, wherein lengths of the first andsecond cables are independently adjustable to permit steering a loadconnected to the fastener.
 2. The lift system of claim 1, wherein theboom is a beam.
 3. The lift system of claim 1, wherein the first cableis linked to a first hydraulic cylinder mounted on the first side of thebeam and the second cable is linked to a second hydraulic cylindermounted on the second side of the beam, wherein the first and secondhydraulic cylinders are independently actuatable to independently adjustthe lengths of the first and second cables.
 4. The lift system of claim1, wherein the wind turbine further comprises a main drive shaft mountedin the nacelle, the main drive shaft having a longitudinal axis orientedat a non-zero angle away from horizontal, and wherein the boom has alongitudinal axis substantially parallel to the longitudinal axis of themain drive shaft.
 5. The lift system of claim 4, wherein the non-zeroangle is in a range of 3-10°.
 6. The lift system of claim 4, wherein thetrolley translates longitudinally along a path substantially parallel tothe longitudinal axis of the main drive shaft.
 7. The lift system ofclaim 1, wherein the winch is mounted on an upper surface of the boom.8. The lift system of claim 1, wherein the winch is mounted underneaththe boom.
 9. The lift system of claim 1, wherein the winch is mounted onthe trolley and moves with the trolley.
 10. The lift system of claim 1,wherein the frame structure comprises: a mounting base mountable on astructure in the nacelle capable of supporting all forces imparted tothe nacelle by the lift system; and, a plurality of upwardly extendingsupport struts, wherein at least one of the support struts issupportable on the mounting base and at least one of the support strutsis mountable at a position in the nacelle proximate a main bearing ofthe wind turbine.
 11. The lift system of claim 10, wherein the pluralityof upwardly extending support struts comprises a first strut mountableon the mounting base over a first gearbox pillow block of the nacelle, asecond strut mountable on the mounting base over a second gearbox pillowblock of the nacelle, a third strut mountable at a first position in thenacelle proximate the main bearing and a fourth strut mountable at asecond position in the nacelle proximate the main bearing.
 12. The liftsystem of claim 11, wherein the trolley extends transversely beyondtransverse sides of the boom, the at least one trolley sheave comprisesa first trolley sheave on a first transverse side of the boom and asecond trolley sheave on a second transverse side of the boom, and theat least one cable is reeved through the first and second trolleysheaves.
 13. The lift system of claim 10, wherein the structure capableof supporting the weight of the lift system comprises pillow blocks of agearbox of the wind turbine.
 14. The lift system of claim 1, wherein thefastener comprises a hook or a lifting lug.
 15. The lift system of claim1, wherein the beam comprises a trolley skidding track on which thetrolley is movably mounted.